[PATCH 4/4] tracing: Fix use-after-free in hist_register_trigger()

[Steven Rostedt]

From: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>

This fixes a use-after-free case flagged by KASAN; make sure the test
happens before the potential free in this case.

Link: http://lkml.kernel.org/r/48fd74ab61bebd7dca9714386bb47d7c5ccd6a7b.1467247517.git.tom.zanussi@xxxxxxxxxxxxxxx

Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace_events_hist.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 19ae135120a3..f3a960ed75a1 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1441,6 +1441,9 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 		goto out;
 	}
 
+	if (hist_data->attrs->pause)
+		data->paused = true;
+
 	if (named_data) {
 		destroy_hist_data(data->private_data);
 		data->private_data = named_data->private_data;
@@ -1448,9 +1451,6 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 		data->ops = &event_hist_trigger_named_ops;
 	}
 
-	if (hist_data->attrs->pause)
-		data->paused = true;
-
 	if (data->ops->init) {
 		ret = data->ops->init(data->ops, data);
 		if (ret < 0)
-- 
2.8.1